Pervasive computing is the trend towards increasingly ubiquitous, connected computing devices in the environment, a trend being particularly brought about by a convergence of advanced electronic—and particularly, wireless—technologies and the Internet.
The goal in pervasive computing is to create a system that is pervasively and unobtrusively embedded in the environment.
Pervasive environments feature complex computer applications that allow mobile users to access ambient services. The area of applicability of these services is very wide and may range e.g. from residential temperature control to customer assistance in a shopping centre as described e.g. in A. Ranganathan and S. McFaddin (Using workflows to coordinate web services in pervasive computing environments. In: Proceedings of the IEEE International Conference on Web Services 2004, pages 288-295, July 2004)
In most existing examples of pervasive services, the mobile end-users act only as clients of complex business processes at least partly executed by the ambient infrastructure.
In the state of the art (Web services tool kit for mobile devices, http://www.alphaworks.ibm.com/tech/wstkmd 2002; S. Berger, S. McFaddin, C. Narayanaswami, and M. Raghunath. Web services on mobile devices—implementation and experience. In Fifth IEEE Workshop on Mobile Computing Systems and Applications, 2003), a distributed computation paradigm has been suggested, where mobile users do not act merely as clients but can also actively participate in the execution of the overall services, providing their resources as it has become possible to run more and more complex applications on mobile devices.
Using such a distributed execution environment, complex interoperations between mobile devices can therefore be envisioned as an extension of the classical workflow concept.
The execution of a workflow by a set of devices in the pervasive environment raises new requirements such as the compliance of the overall sequence of operations with the pre-defined workflow execution plan.
Most of the research in the area of workflow execution in pervasive environments concerns the interaction between end-users and the process.
Particularly, A. Ranganathan and S. McFaddin (Using workflows to coordinate web services in pervasive computing environments. In: Proceedings of the IEEE International Conference on Web Services 2004, pages 288-295, July 2004) discuss a workflow-based architecture to help mobile users of unfamiliar pervasive environments. Moreover, D. Chakraborty and H. Lei (Pervasive enablement of business processes. In: Proceedings of the Second IEEE Annual Conference on Pervasive Computing and Communications 2004. PerCom 2004, pages 87-97, March 2004) discuss human interactions within BPEL processes, where an architecture adapting to workflow users' mobility is introduced. In these architectures end-users participate in workflow only with a low level of implication within the workflow execution managed by the ambient infrastructure.
Quite extensive work on semantic composition of web services basically falls in one of two approaches:                assignment of web services instances at process design time (as described e.g. in V. Agarwal, K. Dasgupta, N. Karnik, A. Kumar, A. Kundu, S. Mittal, and B. Srivastava. A service creation environment based on end to end composition of web services. In Proceedings of the WWW conference, 2005) or        assignment of web services instances at runtime (as described e.g. in D. J. Mandell and S. A. McIlraith. Adapting bpel4ws for the semantic web: The bottom-up approach to web service interoperation. In Proceedings of International Semantic Web Conference, October 2003).        M. G. Nanda, S. Chandra, and V. Sarkar (Decentralizing composite web services. In: Proceedings of Workshop on Compilers for Parallel Computing, January 2003) discuss a decentralised orchestration scheme for web services, in which starting from a centralised BPEL process specification, a distributed one is produced and deployed on already designated web services.        
According to B. Benatallah, M. Dumas, and Q. Z. Sheng. Facilitating the rapid development and scaleable orchestration of composite web services. Distributed and Parallel Databases, 17(1):5-37, 2005 a distributed orchestration platform is implemented for composite web services. Both of these solutions propose distributed composition of web services chosen at the process designing phase, so that they suffer from a static design and far from meeting the requirements of pervasive environments.